Central Nervous System Part III Flashcards
Define/differentiate concussion, contusion, subdural/subarachnoid hematoma, and cerebral edema.
Concussion: temporary alteration in brain function – typically following a blow to the head; repeated concussions can cause cumulative damage
Contusion: permanent damage caused by bruising of the brain
Subdural or Subarachnoid Hemorrhages: ruptured blood vessels bleed into these available spaces; pressure from the blood may compress the brain and cause sudden, neurological decline
Cerebral Edema: swelling of brain associated with traumatic head injury
What is ischemia? What is a cerebral vascular accident (CVA)? How do most CVAs occur?
Ischemia: any tissue deprived of blood supply - can lead to tissue death
Ischemia of brain tissue can be caused by blockage of a cerebral artery by a blood clot
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Define hemiplegia. How do CVAs cause hemiplegia?
Hemiplegia - paralysis on one side of the body often caused by CVA – sensory and speech deficits may also occur
What is a TIA? What is TPA?
Transient Ischemia Attacks (TIA): temporary episodes of reversible cerebral ischemia; often a warning sign of a larger CVA
Tissue Plasminogen Activator (TPA) is the most effective treatment for acute stroke
Define Alzheimer’s Disease. What are some symptoms? What are 2 potential anatomical structures associated with Alzheimer’s Disease that cause neuronal death?
Alzheimer’s Disease (AD) - Progressive, degenerative disease of the brain that results in dementia
Symptoms - memory loss, short attention span, disorientation, eventual language loss, irritability, moodiness, confusion, and hallucinations
Neurofibrillary Tangles: formed from the protein tau inside the neurons; tangles interfere with the neuron’s transport mechanisms and eventually kill the neurons
The brain shrinks as neurons die
Define Parkinson Disease. What are some symptoms? What is a potential cause? What is a treatment?
Parkinson’s Disease - Degeneration of dopamine-releasing neurons of the substantia nigra
The basal nuclei deprived of dopamine become overactive – results in tremors
Overall cause is unknown, but theories exist about mitochondrial abnormalities or protein degradation pathways
Treatment: L-dopa (a dopamine precursor), deep brain stimulation, and gene therapy
Define Huntington Disease. What causes it? What are some symptoms? What is a potential treatment?
Huntington’s Disease
Fatal hereditary disorder caused by the accumulation of the protein huntingtin in brain cells – leads to degeneration of basal nuclei and the cerebral cortex
Onset is often in middle age
Initial symptoms: wild, jerky, “flapping”-like movements; followed by mental deterioration
“Chorea”: excessive, writhing movements; Greek for “dance”
Condition is typically fatal within 15 years
Treatment: drugs that block the effects of dopamine – stem cell implant research is promising
Where does the spinal cord begin? Where does it end?
The spinal cord begins at the foramen magnum and ends at the L1/L2 vertebra
What 2 functions does the spinal cord provide?
Provides 2-way communication between the brain and body
Acts as a major reflex center – reflexes are initiated and completed at the spinal cord
How is the spinal cord protected?
The spinal cord is protected by bone, meninges, and CSF
What can you find in the epidural space? What is the clinical importance of the epidural space?
Epidural Space - cushion of fat and a network of veins in the space between vertebrae and the spinal dura mater
What can you find in the subarachnoid space?
Subarachnoid Space - space between the arachnoid and pia maters; it is filled with CSF
Define and be ready to identify: conus medullaris, filum terminale, denticulate ligaments, cauda equina, ventral median fissure, dorsal median sulcus, and central canal.
The spinal cord terminates in a cone-shaped structure called the conus medullaris
Filum Terminale: a fibrous extension of the conus medullaris covered with pia mater. It extends to the coccyx and anchors the spinal cord.
Denticulate Ligaments: extensions of pia mater that secure the spinal cord to the dura mater
Cauda Equina: collection of nerve roots at the inferior end of the vertebral canal
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Why are there cervical and lumbar enlargements in the spinal cord?
Cervical and Lumbar Enlargements - areas of the spinal cord where the nerves servicing the upper and lower limbs arise
Draw out how spinal nerves exist the spinal cord at each vertebral level.
The spinal cord’s central canal is filled with CSF, and it is continuous with the _______________.
brain’s 4th ventricle
What are the 3 gray columns of the spinal cord? What is located in each column?
Dorsal Horns: interneurons that receive somatic and visceral sensory inputs
Ventral Horns: some interneurons, mostly somatic motor neurons
Lateral Horns: only exist in thoracic and superior lumbar regions; autonomic (sympathetic) neurons that innervate the visceral organs
What is the gray commissure?
Gray Commissure: bridge of gray matter that connects the masses of gray matter on either side of the central canal
Define, know the function of, and be ready to identify: ventral root, dorsal root, and spinal nerve.
Ventral Roots: bundle of motor neuron axons that exit the ventral spinal cord
Dorsal Roots: sensory inputs into the dorsal spinal cord
Dorsal Root (Spinal) Ganglion: cell bodies of the sensory neurons
Spinal Nerves: formed by the fusion of the dorsal and ventral roots
Draw out how the spinal cord’s gray matter is divided into 4 groups.
What are the 3 white funiculi of the spinal cord? What makes white matter white?
Dorsal (Posterior)
Lateral
Ventral (Anterior)
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What type of communication is happening with each direction of white fiber tract?
Ascending: up to the higher centers (sensory inputs)
Descending: from the brain to the spinal cord or to the lower cord levels (motor outputs)
Transverse: from 1 side of the spinal cord to the other (commissural fibers)
The spinal cord is particularly sensitive to _____________________.
Direct pressure
Define paresthesia and paralysis. What are the 2 types of paralysis?
Paresthesia: loss of sensory function; caused by damage to the dorsal roots or sensory tracts
Paralysis: loss of motor function; caused by damage to the ventral roots or ventral horn cells
2 Types: Flaccid or Spastic
Flaccid Paralysis: severe damage to the ventral root or ventral horn cells
- Impulses do not reach the skeletal muscles
- There is no voluntary or involuntary control of the muscles
- Muscles atrophy secondary to disuse
Spastic Paralysis: damage to the upper motor neurons of the primary motor cortex or their axons in the spinal cord
- Spinal more neurons remain intact; muscles are stimulated by reflexes
- There is no voluntary control of muscles, only relfex
- Muscles often shorten permanently (muscle contracture)
Be ready to explain how each type of paralysis occurs and how you would expect it to look in a patient.
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Differentiate paraplegia and quadriplegia. Know (generally) what spinal cord level injuries are likely to result in these conditions.
Paraplegia: transection of the spinal cord between T1 and L1
Quadriplegia: transection of the spinal cord in the cervical region
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What is poliomyelitis? What causes it? What portion of the spinal cord is harmed? What are the short and long term symptoms?
Poliomyelitis
An epidemic in the late 1940s and 1950s – vaccine invented in 1952
Destruction of the ventral horn motor neurons by poliovirus
Symptoms: fever, headache, muscle pain and weakness, and loss of certain somatic reflexes
Muscles atrophy because of paralysis
Death can occur from paralysis of respiratory muscles or cardiac arrest
As a result of progressive neuron loss, survivors often develop postpolio syndrome years later
What is ALS? What might cause it? What portion of the spinal cord is harmed? What is a potential treatment?
Amyotrophic Lateral Sclerosis (ALS)
Also called “Lou Gehrig’s Disease”
Destruction of ventral horn motor neurons and the fibers of the pyramidal tracts
Symptoms: loss of abilities to speak, swallow, and breathe
Death typically occurs within 5 years
Caused by the interaction of environmental factors and genetic mutations involving RNA processing
Treatment: only treatment is a drug that interferes with glutamate signaling called riluzole – glutamate is a neurotransmitter indicated as a potential cause of neuron death in a couple different conditions
